Completing the first mission on an Xbox console grants the player various rewards for use in Halo 4, including Air Assault VISN, C.I.O. RUSH, 'Determined' player stance, DMR STP weapon skin, and 50,000 XP. These bonuses are unlocked after purchasing the Champions Bundle in Halo 4 and entering the 'Flying Colors' glyph on Halo Waypoint. If entered correctly, the next time Halo 4 is launched, a message will thank you for purchasing the bundle and you will unlock the rewards.

A spiritual successor, Halo: Spartan Strike, released for Windows devices, Steam and Apple devices on April 16th, 2015.[13]

Set sometime in 2554, Halo: Spartan Assault's main narrative explores the SPARTAN-IVs' first Spartan Ops during the Battle of Draetheus V.[14][15] This battle is part of the second war between the UNSC and the remnants of the Covenant, which is still being waged during the events of Halo 4.[9][16][17] The story unfolds through the UNSC TACSIM, a historical computer simulation which the SPARTAN-IVs use for combat analysis and training, much like Halo 4's War Games mode,[10][18] though the framing story takes place at some point after Halo 4's campaign.[note 1] This framing structure explains some of the game's arcade-like elements, such as weapons' ability to fire continuously;[14][15] indeed, Roland jests that the TACSIM doubles as "a fun game you can play in your spare time".[19]

The campaign has two protagonists, Spartans Sarah Palmer and Edward Davis, whose first meeting is depicted in the Halo: Initiation limited comic series.[16] Rather than the in-engine cutscenes used in most Halo games, Spartan Assault instead makes use of motion comic-style animations between missions, much like the Terminals in Halo: Combat Evolved Anniversary and Halo 4.[3]Various quotes are displayed in the game's mission loading screens, some acting as gameplay tips while others provide backstory for the events of the game.

The Covenant forces are led by SangheiliZealotMerg Vol. Vol leads a fleet of ships to the planet and the Covenant deploys troops on both Draetheus V and its moonX50. Palmer and Davis lead the UNSC in defending the planet from the Covenant. After thwarting the initial assault, Davis moved to secure the UNSC's Research Facility Alpha and the Forerunner artifact located therein, which appeared to be the Covenant's main target.[22] However, the Covenant resumed their assault and the UNSC feared the research facility would soon be crushed. Palmer, with a Marine detachment, infiltrated artillery positions the Covenant had set up and destroyed them.[23] Spartan Davis later noticed the Covenant's heavy reliance on dropship insertion. Davis realized they would be vulnerable to focused anti-aircraft fire, so, using M9 Wolverines, he began establishing air defenses west of the facility at a location designated Glacial Perch.[24]

While Spartan Davis was successful in slowing the enemy advance, the Covenant forces were too overwhelming. Sarah Palmer began fighting her way upstream through the invasion in an attempt to reach one of the northern outposts. Her plan was to destroy Covenant air support and give the AV-14 Hornets a chance to land near the outposts. The ultimate goal was to get off X50 and warn Draetheus V of the Covenant invasion. Within an hour of their arrival at X50, the Covenant owned the moon. Despite the ferocity of the assault on X50, the UNSC forces on Draetheus V had no idea anything was going on because the planet's unique magnetic resonance frequently made off-world communication nearly impossible.[25]

While Davis defends the moon, Palmer and a small amount of UNSC forces remains on Draetheus V, outgunned and out-manned. The Covenant attack Draetheus V's main military outpost, Faraday Base, and breach the first defense lines before the base's sentry turrets were fully operational.[26] After securing Faraday, Palmer began trying to establish the location of the Covenant officers leading the invasion. After taking significant losses, Marines of the 21st Scout platoon had managed to uncover a set of promising coordinates. After tracking the officers down, she quickly eliminated them.[27]

As Spartan Palmer led the charge on Draetheus V, Spartan Davis continued to face considerable enemy threat on the moon. Furthermore, it was revealed that X50 was not a natural moon after all, but a Forerunner megastructure capable of constructing and destroying planets. Upon finding his way into the control center, Merg Vol tuned X50's main weapon on Draetheus V and began to dismantle the planet. The Covenant forces activated the primary weapon of the X50 construct. Directed toward the planet, the beam began to disintegrate Draetheus V, destabilizing it.[28] Enormous slabs of rock were slowly floating away from the planet's surface and both UNSC and Covenant troops were scrambling to get to safety as the UNSC continued to evacuate the planet.[29] The Covenant continued to attack the planet and the UNSC quickly realized that Draetheus V was ill-prepared for a full evacuation. There was not enough transportation to allow everyone to leave Draetheus V. However, the UNSC raided a Covenant airfield and stole numerous Covenant aircraft. With Palmer's help, 23 Covenant aircraft carrying civilians made it off the planet.[30]

In a stroke of luck, the UNSC Eminent Domain was able to outmaneuver Covenant forces in orbit over the moon and offer some support by deploying ODSTs to the southern Mirror Flats. The 3rd Helljumper Platoon was the first to land on Draetheus V's moon. Their drop zone was less than a mile from Alpha facility but the landing scattered them across the razor sharp rock face of the Glacial Perch. They were quickly surrounded by Covenant infantry and taking heavy losses, but Davis came to their assistance.[31] Davis connected with UNSC combat technicians who believed they could render the Forerunner structure inert; they just needed the chance to get inside the structure.[32] Davis and the remaining Marines assisted the combat technicians securing the Forerunner structure while the Covenant reinforcements did everything in their power to stop the technicians. With supporting sniper fire from higher grounds, Davis and his men were able to buy the technicians just enough time to do their work. However, even with their job complete, it was too late for Draetheus V. The planet was already breaking apart.[33]

Davis' last stand.

While defending the moon, Spartan Davis was killed by an overwhelming amount of Sangheili forces. With transportation secured, one last hurdle remained in getting the colonists safely off of Draetheus V. The leader of the Covenant forces, Merg Vol, was still present on moon X50, providing the remaining Covenant forces with a rallying point and cry. If the colonists were to leave Draetheus V's orbit alive, Merg Vol would need to be terminated. Palmer suspected the Covenant's officer on Draetheus V, Parg Vol had a personal transport hidden away. After completing the evacuation operation, locating Parg Vol's ship became Palmer's highest priority. After fighting through heavy Covenant forces she was able to locate Vol's Phantom and used it to get to X50.[34] Having successfully piloted the Phantom through the Covenant fleet orbiting Draetheus V's moon, Palmer was able to land south of Merg Vol's camp, out of range of his turrets.[35]

Palmer approaching Vol.

Merg Vol was convinced he had been chosen by his gods to wield the power contained within the Forerunner structure. Having spent considerable resources to unlock its secrets, Vol managed to activate the structure's emergency defenses. With the deadly defenses at his command, Vol had become extremely dangerous. Unable to contact Spartan Davis since landing on Draetheus V's moon, Palmer prepared to battle Vol on her own. Vol's exact location had not been difficult to find: the direct area at the foot of the Forerunner structure was littered with a trail of dead UNSC soldiers. After facing Merg Vol's final forces and Forerunner beam turrets, she engaged Merg Vol himself. Despite a difficult fight, Palmer was able to overtake Vol and executed him with her M6H magnum.

With Merg Vol killed and the Covenant forces were defeated and the surviving colonists of Draetheus V were able to safely evacuate the system. After killing Vol, Palmer sabotaged the Forerunner device on X50.[36]

Shortly after the battle, the UNSC discovered a looping transmission of low-frequency static from X50. Palmer and UNSC forces returned to the moon to investigate. However, the UNSC quickly realized that Covenant forces remained on the moon. After fighting through numerous Covenant soldiers, Palmer discovered that the message had originated from Spartan Davis, moments before his death, and that Davis' final impressions had been absorbed into a Forerunner device. She shut the device down in order to allow her friend to pass away peacefully.[37]

As a "twin-stick" top-down shooter title, Halo: Spartan Assault is developed primarily for touchscreen platforms. The default controls for the game use some of the common control mechanics of touchscreen games: the movement control is located on the left screen whereas the aiming and firing control is located on the right. Halo's staple abilities, (such as grenade with a single button and using vehicles seamlessly), are readily accessible to the player and are placed next to the aiming and firing controls for ease of use.[39]

On Windows 8 PCs and tablets, the game can also be played with a mouse and keyboard. Keyboard controls use a standard shooter format: the "WASD" key group controls movement and the mouse is for aiming and firing. On August 29, an update was applied to the game which enables the use of an Xbox 360 controller as well.[39] The console versions of the game feature an altered control scheme in which the player must press the Right Trigger in order to fire weapons; in contrast, the other versions do not distinguish between the "look" and "fire" controls.[38]

The Xbox 360 and Xbox One versions of the game include a two-player online cooperative mode. In this mode two Spartans battle against hordes of Flood forms across five missions.[1] The also mode features never-before-seen weapons and equipment, including a machine pistol (which is dual-wielded like the M7), a teleportation armor ability, and a what appears to be a "cryo bomb" which emits a cloud that the Flood cannot penetrate.[38][40]

Vanguard Games began development of Halo: Spartan Assault around April 2012 for the Windows 8 platform, before the announcement of Windows Surface.[54] During initial development, Vanguard experimented with several prototypes by bringing the traditional Halo first-person shooter experience to mobile devices, only to find the gameplay wholly unsuitable for the platform.[54] The game's AI system is managed by HAVOK, the same AI system management technology used in Halo 4.[55] The Microsoft Surface Pro version of the game runs at 60 frames-per-second; the Xbox One versions runs at the same frame rate with a native 1080p resolution.[38] The Windows Phone 8 and PC versions are locked at 30 FPS.[54] The game's top-down view and stylization result in an aesthetic very similar to that of Halo Wars.

The sandbox features weapons, vehicles, and armor styles from throughout the series' past. Most of the UNSC's arsenal from Halo 4 is represented in Spartan Assault; indeed, all but one usable UNSC weapon comes from Halo 4. The Covenant's arsenal is instead an eclectic mix of weapons from previous games, notably featuring the focus rifle and plasma repeater from Halo: Reach. Several vehicles and stationary weapons which originated in Halo Wars are virtually unchanged from their incarnations in that game, aside from improved textures. The Covenant Wraith and Banshee also appear to use their models from Halo Wars, evidenced by the former's plasma turret and the latter's canard layout.

Aside from Merg Vol, the Covenant species are based on their appearances in earlier media rather than their Halo 4 incarnations. Specifically, the Grunts, Elites, and Jackals have the physiology of their Halo: Reach counterparts and wear corresponding armor. The Brutes and Drones are instead represented with their designs from Halo 3 and Halo 3: ODST.

In-game statistics are integrated across the four Microsoft platforms: Windows 8, Windows Phone 8, Xbox 360, and Xbox One. Medals unlocked, XP earned, and cR purchased are each deposited into a single repository. Challenge/Assault Ops progress carries across all platforms.

Mission progress is recorded individually for each platform, and each platform features its own leaderboards. Achievements must be unlocked by playing the game on each platform individually, however some achievements (i.e. 117, Extra Credit, Pension Plan) are unlocked via accomplishments which are recorded across platforms, and therefore unlocking the achievement on one platform can contribute to or even complete the achievement on the others.

Steam does not feature this integration. Progress on this platform does not contribute to the others. Similarly, Halo Waypoint does not record stats, progress or achievements on Steam, nor do Steam achievements contribute to the player's Gamerscore, as the platform utilizes a different profile.[56]

The game is closely integrated with the player's experience in Halo 4 where players can unlock experience points, new achievements, and an emblem for their Halo 4 account.[9] After purchasing the Champions Bundle Pack or the Bullseye Map Pack, the game will unlock:

Halo: Spartan Assault generally received mixed reviews upon release; the game has a weighted aggregate rating of 71/100 on Metacritic, based on sixteen reviews.[60] Pocket Gamer's Harry Slater and Destructoid's Chris Carter wrote that while Spartan Assault was not going to be a Windows 8 "killer app", it was a worthwhile purchase for gamers on the Windows 8 platform. Carter stated "Despite its lack of any remarkable or "must have" features, it still manages to be a fairly decent top-down shooter."[61]

Multiple reviewers praised the game for its authentic Halo look and feel. Kyle Hillard from Game Informer called Spartan Assault "a true Halo game, even if the series’ signature scope and size are scaled down", with the game featuring familiar Halo moments, enemies, and sounds. Although the game's checkpoint system was criticised, with some critics claiming it to be nearly non-existent. Hillard stated that it was "Spartan Assault's big shortcoming".[62]Spartan Assault was criticised for being repetitive, dull and unmemorable. IGN's Dan Stapleton gave the game's Xbox One version a 5.8 out of 10 rating, stating "The top-down perspective turns the distinctive Halo arsenal into a bunch of pretty boring guns."[63]

The microtransaction features of Spartan Assault were generally negatively received. While reviewers such as Destructoid's Carter felt that the microtransactions could be ignored and did not impact enjoyment of the game,[61] Hillard wrote that "it’s hard not to feel as though an important part of the game is being withheld after buying into the agreed-upon price of admission."[62] IGN's Stapleton stated "the worst thing about Spartan Assault is its obnoxious microtransactions."[63]

Jake Valentine from GameZone gave the Xbox One version a less generous 5/10, stating "Halo: Spartan Assault is a soulless, boring, chore of a game. The small glimpses of fun arcade like gameplay are drowned away by frustration and money grabbing."[64]

^Roland was activated on December 5, 2557, roughly five months after the First Battle of Requiem, to replace Infinity's previous AI, Aine. The game's framing story thus takes place after the events of Halo 4's campaign, though when it occurs in relation to Spartan Ops is unclear. However, Halo: Escalation indicates that Infinity returned directly to Earth after Requiem's destruction, suggesting that the framing narrative takes place in the gap between Roland's creation and the Second Battle of Requiem.